Not So Kind: Weed Growers Suck Down 1 Percent of All U.S. Electricity

Weed-loving treehuggers, you are on notice. The cultivation of your beloved endo, or marijuana grown indoors, consumes a whopping 1 percent of the entire nation's electricity. That's enough juice to power 2 million American homes. All those grow lights, it turns out, inhale some serious juice.

This is according to the work of Evan Mills, a longtime researcher at Lawrence Berkeley National Laboratory (who worked on this on his own time, he makes sure to note). Mills released his eye-popping independent study last week. As you can see below, he writes in the beautifully staid language of a scientist:

The emergent industry of indoor Cannabis production results in prodigious energy use, costs, and greenhouse-gas pollution. Large-scale industrialized and highly energy-intensive indoor cultivation of Cannabis is driven by criminalization, pursuit of security, and the desire for greater process control and yields...

In California, the top-producing state—and one of 17 states to allow cultivation for medical purposes—the practice is responsible for about 3% of all electricity use.

On top of his work at Lawrence Berkeley and his heady side-research, Mills is a member of the U.N's Intergovernmental Panel on Climate Change, the world's preeminent climate change research front. So it was obvious that he'd translate these electricity demands into their effect on the climate.

The yearly greenhouse-gas pollution (carbon dioxide, CO2) from the electricity plus associated transportation fuels equals that of 3 million cars.

Wondering about that loose joint you scored at Coachella? Mills writes that "a single Cannabis cigarette represents 2 pounds of CO2 emissions, an amount equal to running a 100-watt light bulb for 17 hours with average U.S. electricity."

Before you renounce weed entirely (as if you were about to) keep in mind that this massive carbon footprint is caused by the lights and fans and air filters of indoor cultivation. Outdoor weed plantations may have their own issues, but energy use isn't a big one. What's more, Mills does bring up the serious potential for energy efficiency upgrades, estimating that efficiency improvements of 75 percent are conceivable.